Diaphragm feed pump



Jan. 12, 1960 SCHAURTE 2,920,573

DIAPHRAGM FEED PUMP Filed Dec. 19, 1957 United i States Patent ODIAPHRAGM FEED PUMP Paul Schaurte, Vaduz-Bartlegrosch, LiechtensteinApplication December 19, 1957, Serial No. 703,840 Claims priority,application Germany December 22, 1956 9 Claims. (Ci. ID3- 44) Thepresent invention relates to a diaphragm feed or vacuum pump, and moreparticularly to improvements in a pump of a type which has a check valvewlthin the outlet conduit, and which essentially comprises two resilientdiaphragms, at least one of which is extensible, and between which anincompressible pressure transmitting iluid is provided. One of thesediaphragms is adapted to be moved back and forth at a constant strokeand thus acts through the pressure transmitting uid upon the otherdiaphragm to compress the latter into an annular recess in a wall of thepump housing. The volume of the chamber enclosed by the two diaphragmsand containing the pressure transmitting fluid remains constant duringboth the compression and suction strokes. The outer surface of thepositively reciprocated diaphragm of this type of pump is generallyexposed to the normal atmospheric pressure with the result that thisdiaphragm easily bulges outwardly when the pressure in the pump chamberexceeds a certain value. In other words, if the pump is to operateproperly, the pressure of the medium to be conveyed may never exceedsuch value. A further disadvantage of a pump of this type is that itcontains considerable dead space even though the diaphragm covering thepump chamber might fully engage with the opposite walls thereof duringthe compression stroke. Furthermore, this type of pump required a checkvalve in both the inlet and outlet conduits thereof.

It is an object of the present invention to provide a diaphragm feedpump of the above-mentioned type which is especially adapted to be usedas a vacuum pump, and overcomes all of the above-mentioned disadvantagesof similar pumps of previous designs.

For attaining this object the present invention provides a diaphragmpump in which the outer side of the driving diaphragm, that is, the sideopposite to the side facing toward the driven diaphragm covering thepump chamber, is maintained under a pressure which is higher than themaximum pressure within the pump chamber, so that this pressure willproduce the inward or compression stroke, while the outward or suctionstroke will be produced by a driving means through a traction memberwhich is positively connected to the driving diaphragm and may form anintegral part of this diaphragm. Particular advantages will also beattained if the outer ends of both diaphragms which enclose the pressuretransmitting uid are clamped within the same plane.

Further objects, features, and advantages of the present invention willbecome apparent from the following detailed description thereof,particularly when read with reference to the accompanying diagrammaticdrawing of one preferred embodiment of the invention.

As illustrated in the drawing, a housing 1 contains a shaft 2 which isrotatably mounted in suitable bearings, not shown, and extends throughone side wall of housing 1 by being sealed toward the outer atmosphereby suitable packing means, not shown. Shaft 2 carries an eccentric cam 3which is surrounded by a disk which consists of two parts 4 and 5between which a resilient member 6 is clamped which is connected to anouter or driving diaphragm 7 or may form an integral unit therewith.Diaphragm 7 is preferably reinforced at its central part by a cup-shapedmember 8.

Diaphragm 7 and a second diaphragm 9 are clamped together between thehousing parts 1 and 10 by means of bolts 11 and form a chamber 17 whichis filled with an incompressible iiuid, for example, oil. Housing part10 which may form a solid base or cover of the pump contains an inletconduit 12 at the center thereof. The opening of conduit 12 in the pumpchamber 13 may be covered by suitable means, not shown, so as to protectdiaphragm 9 from being damaged when it engages with the edge of thisopening. This pump chamber 13 is formed by an annular recess in housingpart 10` which also has an outlet opening into an outlet conduit 14 inwhich a check valve is mounted which may consist, for example, of aplate 16 which is acted upon by a spring 15. The outer chamber 18containing the driving elements may be filled with a gaseous or liquidmedium under a pressure higher than the maximum pressure which is to beexpected within pump chamber 13. Chamber 18 may also be connected by aconduit 19 to a suitable pump 20 or pressure tank, although a pressureof suicient strength may once be provided in chamber 18 and the same maythen be closed.

Since chamber 18 contains a higher pressure than pump chamber 13, theresilient member 6 will only be subjected to traction. When drive shaft2 rotates, diaphragm 7 can move in the direction toward housing part 10,whereby diaphragm 9 will also move into pump chamber 13 because of theincompressible fluid contained. between the two diaphragms 7 and 9.Diaphragm 9 will then at first engage with and shut oif the mouth of theinlet conduit 12, whereupon the respective medium to be conveyed whichis contained in pump chamber` 13 will be pressed by diaphragm 9 throughcheck valve 15, 16' into the outlet conduit. At the further rotation ofshaft 2, cam 3 will draw diaphragm 7 through the connecting member 6back to the starting position and thereby produce an underpressure inpump chamber 13 which sucks a new supply of the medium to be conveyedthrough intake conduit 12 into the pump chamber, while check valve 15,16 prevents the medium already within outlet conduit 14 from beingsucked back into the pump chamber. This operation is then repeated atevery revolution of drive shaft 2.

Although the invention has been illustrated only with reference to asingle two-diaphragm pump, it will be evident that several such pumpsmay be mounted concentrically to drive shaft 2 or that two such pumpsmay be mounted so that their inlet conduits 12 extend along the samestraight line. If two or more pumps are provided and such pump assemblyis to be used as a vacuum pump, it will be advisable to connect thesepumps in series so as to operate like a multi-stage pump. It two or morepumps according to the invention will be driven by a single drive shaft,the volume of al1 charnbers 18 will remain constant and they will thenin effect constitute a single chamber. In this event, chambers 18 may befilled with an incompressible uid which is acted upon by a pump or thelike.

Although my invention has been illustrated and described with referenceto the preferred embodimentf thereof, I wish to have it understood thatit is in no way limited to the details `of such embodiments, but iscapable of numerous modifications within the scope of the ap pendedclaims.

Having thus fully disclosed my invention, what I claim is:

1. In a membrane pump, in combination, a pump -housing; membrane meansarranged in said housing subdividing the same into a pumping chamber anda closed pressure chamber, said membrane means being deformablyalternately movable'in said housing in a direction away from saidpumping chamber toward said pressure chamber and vice versa; inlet andoutlet means communicating with said pumping chamber; a compressible uid`under pressure permanently filling said pressure .chamber andpermanently tending to move said mem- *brane means in direction towardsaid pumping chamber, said uid exerting its action upon said memb-ranemeans substantially over the entire free surface thereof; inlet meanscommunicating with said pressure chamber for supplying and maintainingin the latter a pressure Which at -all times is higher than the pressurein said :pumping chamber; and means for periodically moving saidmembrane means in a direction away from said pumping chamber toward saidpressure chamber, Whereby during movement of said membrane means thesame is permanently supported over substantially the entire surfacethereof by said pressure uid in said pressure cham- -ber so as toprevent undesired buckling of said membrane means.

`2. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing sub- `dividing the same into a pumping chamberand a closed pressure chamber, said membrane means being deformablyalternately movable in said housing in a direction away from saidpumping chamber toward said pressure chamber and vice versa, saidmembrane means including a flexible pumping membrane facing said pumpingcharnber and a flexible driving membrane facing said pressure chamber,said membranes being spaced so as to form a pressure-transmitting spacetherebetween; inlet and outlet means communicating with said pumpingchamber; a non-compressible uid filling said pressure-transmittingspace; a compressible fluid under pressure permanently vfilling saidpressure chamber and permanently tending to move said driving membranein direction toward said pumping chamber, said fluid exerting its actionupon said driving membrane substantially over the entire free surfacethereof; inlet means communicating with said pressure chamber forsupplying and maintaining in the latter a pressure which at all times ishigher than the pressure in said pumping chamber; and means forperiodically vmoving said driving membrane in a direction away fromNsaid pumping chamber toward said pressure chamber,

whereby during movement of said driving membrane the same is permanentlysupported over substantially the entire surface thereof by said pressurefluid in said pressure chamber so as to prevent undesired buckling ofsaid driving membrane.

3. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing subdividing the same into a pumping chamberanda closed ,pressure chamber, said membrane means being deformablyalternatively movable in said housing in a direction ,away from saidpumping chamber toward said pressure chamber and vice versa; aprojection on said pump housing extending into said pumping chambertoward said .membrane means, said projection being formed with an entirefree surface thereof; inlet means communicating with said pressurechamber for supplying and maintaining in the latter a pressure which atall times is higher than the pressure in said pumping chamber; and meansfor periodically moving said membrane means in a direction away fromsaid pumping chamber toward said pressure chamber, whereby duringmovement of said membrane means the same is permanently supported oversubstantially the entire surface thereof by said pressure iluid in saidpressure chamber so as to prevent undesired buckling of said membranemeans.

4. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing subdividing the same into a pumping chamber anda closed pressure chamber, said membrane means being deformablyalternately movable in said housing in a direction away from saidpumping chamber toward said pressure chamber and vice versa, saidmembrane means including a Lilexible pumping membrane facing saidpumping chamber anda exible driving membrane facing said pressurechamber, said membranes having peripheral portions secured to saidhousing and central portions spaced apart so as to form apressure-transmitting space therebetween; inlet and outlet meanscommunicating with said pumping chamber; a non-compressible fluidfilling said pressuretransmitting space; a compressible iluid underpressure permanently filling said pressure chamber and permanentlytending to move said driving membrane in direction toward said pumpingchamber, said Huid exerting its action upon said driving membranesubstantially over the entire free surface thereof; inlet meanscommunicating with said pressure chamber for supplying and maintainingin the latter a pressure which at all times is higher than the pressurein `said pumping chamber; and means for periodically moving said drivingmembrane in a direction away from said pumping chamber toward saidpressure chamber, whereby during movement of said driving membrane thesame is permanently supported over substantially the entire surfacethereof by said pressure fluid in said pressure chamber so as to preventundesired buckling of said driving membrane.

5. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing subdividing the same into a pumping chamber anda closed pressure chamber, said membrane means being deformablyalternately movable in said housing in a direction away from saidpumping chamber toward said pressure chamber and vice versa, saidmembrane means including a flexible pumping membrane facing said pumpingchamber and a iiexible driving membrane facing said pressure chamber,said membranes having peripheral portions jointly secured to saidhousing along a common plane and central portions spaced apart so as toform a pressuretransmitting space therebetween, a non-compressible fluidfilling said pressure-transmitting space; inlet and outlet meanscommunicating with said pumping chamber; a compressible fluid underpressure permanently filling said pressure chamber and permanentlytending to move said driving membrane in direction toward said pumpinglchamber, said fluid exerting its action upon said driving membranesubstantially over the entire free surface thereof; inlet meanscommunicating with said pressure chamber for supplying and maintainingin the latter a pressure which at all times is higher than the pressurein said pumping chamber; and means for periodically moving said drivingmembrane in a direction away from said pumping chamber toward saidpressure chamber, whereby during movement of said driving membrane thesame is permanently supported over substantially the entire surfacethereof by said pressure iluid in said pressure chamber so as to preventundesired buckling of said driving membrane.

-6. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing submembrane means dividing the same into apumping chamber and a closed pressure chamber, said membrane means beingdeformably alternately movable in said housing in a direction away fromsaid pumping chamber-toward said pressure chamber and vice versa; inletand outlet means communicating with said pumping chamber; a compressibleuid under pressure permanently filling said pressure chamber andpermanently tending to move said membrane means in direction toward saidpumping chamber, said uid exerting its action upon said membrane meanssubstantially over the entire free surface thereof; inlet meanscommunicating with said pressure chamber for supplying and maintainingin the latter a pressure which at all times is higher vthan the pressurein said pumping chamber; a resilient member mounted on said membranemeans in said pressure chamber; and means for periodically moving saidresilient member in a direction away from said pumping chamber towardsaid pressure chamber, whereby during movement of said the same ispermanently supported over substantially the entire surface thereof bysaid pressure uid in` said pressure chamber so as to prevent undesiredbuckling of said membrane means.

7. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing subdividing the lsame into a pumping chamberand a closed pressure chamber, said membrane means being deformablyalternately movable in said housing in a direction away from saidpumping chamber toward said pressure chamber and vice versa; inlet andoutlet means communicating with said pumping chamber; a compressible uidunder pressure permanently filling said pressure chamber and permanentlytending to move said membrane means in direction toward said pumpingchamber, said uid exerting its action upon said membrane meanssubstantially over the entire free surface thereof; a resilient membermounted on said membrane means in said pressure chamber; inlet meanscommunicating with said pressure chamber for supplying and maintainingin the latter a pressure which at all times is higher than the pressurein said pumping chamber; and eccentric means rotatable in said pressurechamber for periodically moving said resilient member in a directionaway from said pumping chamber toward said pressure chamber, wherebyduring movement of said membrane means the same is permanently supportedover substantially the entire surface thereof by said pressure uid insaid pressure chamber so as to prevent undesired buckling of saidmembrane means.

8. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing subdividing the same into a pumping chamber anda closed pressure chamber, said membrane means being deformablyalternately movable in said housing in a direction away from saidpumping chamber toward said pressure chamber and vice versa; inlet andoutlet means communicating with said pumping chamber; a compressible uidunder pressure permanently filling said pressure chamber and permanentlytending to move said membrane means in direction toward said pumpingcham ber, said iluid exerting its action upon said membrane meanssubstantially over the entire free surface thereof; inlet meanscommunicating with said pressure chamber for supplying and maintainingin the latter a pressure which at all times is higher than the pressurein said pumping chamber; a resilient member integral with a portion ofsaid membrane means in said pressure chamber; and means for periodicallymoving said resilient member in a direction away from said pumpingchamber toward said pressure chamber, whereby during movement of saidmembrane means the same is permanently supported over substantially theentire surface thereof by said pressure uid in said pressure chamber soas to prevent undesired buckling of said membrane means.

9. In a membrane pump, in combination, a pump housing; membrane meansarranged in said housing subdividing the same into a pumping chamber anda closed pressure chamber, said membrane means being deformablyalternately movable in said housing in a direction awayA from saidpumping chamber toward said pressure chamber and vice versa, saidmembrane means including a flexible pumping membrane facing said pumpingchamber and a flexible drilling membrane facing said pressure chamber,said membranes being spaced so as to form a pressure-transmitting spacetherebetween; inlet and outlet means communicating with said pumpingchamber; a non-compressible uid filling said pressure-transmittingspace; a substantially rigid backing member in saidpressure-transmitting space for backing contact with said drivingmembrane; a compressible fluid under pressure permanently filling saidpressure chamber and permanently tending to move said driving membranein direction toward said pumping chamber, said fluid exerting its actionupon said driving membrane substantially over the entire free surfacethereof; inlet means communicating with said pressure chamber forsupplying and maintaining in the latter a pressure which at all times ishigher than the pressure in said pumping chamber; and means forperiodically moving said backing member in a direction away from saidpumping chamber toward said pressure chamber, said backing membercontacting said driving membrane and moving the same toward saidpressure chamber, whereby during movement of said driving membrane thesame is permanently supported over substantially the entire surfacethereof by said pressure uid in said pressure chamber so as to preventundesired buckling of said driving membrane.

References Cited in the le of this patent UNITED STATES PATENTS1,691,128 Redmond Nov. 13, 1928 2,575,398 Schroeder Nov. 20, 19512,700,340 Wood Jan. 25, 1955 FOREIGN PATENTS 305,235 Great Britain Feb.1, 1929

